Turntable for phonograph records



March 6, 1934. H. Q HARRlsON 1,950,109

TURNTABLE FOR PHONOGRAPH RECORDS Filed June 25, 1931 /N VEN TOR By H. C.HARP/SON ATTORNEY Patented Mar. 6, 1934 i, sans aan UNITED STATES HenryC. Harrison, Port Washington, N. Y., assignor to Bell TelephoneLaboratories, Incorporated, New York, N. York Y., a corporation of NewApplication June 25, 1931, Serial No. 546,704 '7 Claims. (Cl. 274-39)This relates to phonographs and particularly to the turntables thereof.

In the ordinary phonograph using hard rubber or other rigid discrecords, the turntable usually employed is simply a heavy, flat, metalcylinder with a locating mandrel in the center. For the newer, thin,flexible records, such a turntable cannot be used advantageously, sincethese records have a tendency to warp and buckle, which w makes theirsurfaces irregular and the reproduction therefrom poor unless suchirregularities are removed.

It is the object of the present invention to provide a turntable forilexible records which will 35 cause the record to present a regularsurface to its cooperating translating device.

The novel means used to accomplish this object comprises a turntablehaving located about its periphery a-number of springs adapted to exert20 an outward radial force upon the record to stretch it, therebystraightening out the warped or buckled portions.

In the accompanying drawing part of the specification:

Fig. l1 is a perspective of a preferred embodiment of the novelturntable showing a record in place;

Fig. 2 is a sectional in detail; and

Fig. 3 is an enlarged portion of a record illustrating one type ofaperture.

Referring now to Fig. l, l0 is a turntable made suitably heavy to smoothout some of the vibration usually occurring in phonographic apparatusand arranged in a concentric circle -near the periphery of the turntableand integral with it are a number of vertical springs 11. These springsmay be sixteen in number or more depending largely upon the uniformityof tension desired in the record.

The record l2 is of the thin nexible type and is designed with a blankmargin in which are punched or drilled a series of circular aperturescorresponding in number to the springs. The apertures are located,however, in a circle the diameter of which is slightly smaller than thatof the spring circle so that When the record is in place the springswill be bent radially inward and will thereby exert an outward restoringforce O upon the record which force produces a radial tension in therecord.

One form of spring which may be used is shown in detail in Fig. 2. It iscomprised of a short length of steel music wire 1l, .044" in diameterpressed into a holding member 13 which is forced which forms a elevationshowing a spring into a piece of tubing le. The tubing is held by a setscrew 15 in an opening in the turntable. The springs are provided withconical caps 16 to prevent the record from creeping up on the spring andeventually disengaging from it entirely. Toe @Q conical shape isnecessary to facilitate the remoVal of the record from the turntable. Anabutting edge on the underside of the cap would cause the record to jamand the springs would have to be pressed in toward the center individ- 65` ually to release them.

The record is placed on the turntable by threading it on the locatingmandrel in the usual manner and then rotating it until the apertures inthe record are over the springs. By running the i0 hand around the edgeof the record the springs are snapped through the apertures and therecord is tensioned.

For ease of operation the apertures may be designed as shown in Fig. 3.The part A is made 35' large enough to iit over the cap and B is made ofa diameter to accommodate the lower portion of the conical section ofthe spring. The record can now be placed flat on the turntable withoutthe necessity of snapping the springs. To ten- 80 sion the record it isrotated slightly in the direction indicated, causing the spring to slidealong the oblique portion D until it snaps into B. The portion Ddisplaces the spring radially and thereby tensions it.

The invention has been described with reference to a particularembodiment for purposes of illustration but its scope is not to belimited to that disclosed in the drawing and specication.

What is claimed is: SQ

1. In a phoncgraphic machine, a turntable, a flexible record thereon,and springs secured to the turntable `for tensioning the recordradially.

2. In a phonographic machine, a turntable, a flexible record thereon,and springs secured to 9.5 the turntable for tensioning the recordradially, each of said springs comprising a member rigidly secured atone end to the turntable and adapted to be iiexed radially of theturntable.

3. In a phonographic machine, a turntable, a 90 flexible record thereon,and springs secured to the turntable for tensioning the record radially,said springs comprising a member rigidly secured at one end near theunderside of the turntable and adapted to be flexed radially of theturntable 05 at its free end, and a conical cap at the free end M formaintaining said members in contact with the record.

4. In a phonographic machine, a turntable, a flexible record thereon,provided with apertures 1x10 spaced equidistantly about the edge thereofand a plurality of springs secured to the turntable and extendingthrough the apertures in the record to tension the record radially.

5. In a phonographic machine, a turntable, a exible record thereon,provided with apertures spaced equidistantly about a circle locatedconcentrically with and in proximity to the edge thereof, correspondingsprings secured to the turntable and arranged in a concentric andslightly smaller circle and adapted to snap through the apertures toexert an outward radial force upon the record.

